L. Frank Baum’s The Wonderful Wizard of Oz was the first book in what became a fourteen-volume series. It sold nearly 15,000 copies within a month of its publication in September 1900 and remains the most popular of the Oz books — not least of all because it’s the only one illustrated by W. W. Denslow, whose depictions of Dorothy, Toto, and all the other creatures and landscapes of Oz have become so iconic as to be inseparable from Baum’s story.